Now that Christmas and many other celebrations gather people around a table, it is important to know about the risks we take and the science behind them. Vaccines are the number one weapon humankind has developed in the last decades to fight many diseases using or boosting our natural immune system. Vaccines allow our bodies to activate cells and antibodies to attack countless different invasive bugs that otherwise would create dreadful effects in our bodies. But what do we know about the antibodies that are generated against COVID-19? How often should we re-boost our immune systems?

Antibodies from COVID-19 vaccine in 2021 study declined 57% after six months

A study conducted on 787 healthcare workers in Italy who received the Pfizer-BioNTech vaccine in 2021 showed a 57% decline in serum levels of anti-SARS-CoV-2 antibodies six months after their second dose of the vaccine. The study, a collaboration between researchers from the Texas Biomedical Research Institute (TBRI; San Antonio, TX) and the University of Verona (Italy), was accepted for publication in the Journal of Medical Biochemistry in November 2021.

Two-thirds of the healthcare workers were females. The ages of the group ranged from 21 to 75 years with a mean age of 44 years. Of the 787, 33 individuals were 65 years old or older. The group received two doses of the vaccine three weeks apart. Antibody levels were measured before the first vaccine dose, immediately before the second vaccine dose, then at one, three, and six months after the second vaccine dose. A peak in the number of antibodies was observed at the 1-month mark with levels declining 37% from the peak after three months and 57% from the peak after six months.

Age differences

While not detailed in the available pre-print, data from the TBRI website shows that the percentage declines at three and six months were roughly similar between persons under 65 and those 65 and older (Fig 3). However, the researchers reported that the 6‑month post-vaccination absolute serum levels of anti‑SARS‑CoV‑2 antibodies in subjects 65 years and older were less than half of those under 65 years old.

 

 

 

 

 

 

 

 

 

 

Gender variation

Another aspect of the data not broken out in the pre-print (but detailed on the TBRI website) were the gender differences in initial antibody production and subsequent declines. Again, these were comparable in terms of percentage reductions in antibody levels (Fig 3), but females in both the < 65 and ≥ 65 groups produced much higher absolute serum antibody levels than males in either age cohort (Fig 2).

 

 

 

 

 

 

 

 

 

 

 

Vaccine booster shots

These results have obvious implications for the importance of vaccine booster shots, especially for those 65 years and older. The dramatic 6-month decline in antibodies against a coronavirus, whether after a vaccine or actual infection, is perhaps not surprising. Estimates are that 20% of cases of common cold, an insufficiently studied disease, are caused by one of the four other coronaviruses that can infect humans. Little is known of how well immunity to these coronaviruses is maintained, but clearly some individuals contract several colds per year. If one is intent on avoiding COVID-19 infection, if for no other reason than the unknowns that still surround “long COVID,” getting a booster shot annually would seem prudent.

COVID-19 variants present and future

Another aspect of the pandemic that these results bear upon is the effectiveness of current and future vaccines on SARS-CoV-2 variants. As detailed in the Marin Bio blog post on the 2021 CDC VISION network study that compared antibody levels stimulated by either of the two mRNA vaccines with those from actual infection, the vaccines are quite effective in driving production of anti-SARS-CoV-2 antibodies. Antibody-mediated immunity is a numbers game; quantities matter. T cells are even more resistant to variations in foreign antigens. As a result, most people (other than the most immunocompromised, at-risk individuals) should continue to expect the high levels of protection from infection that have been observed to date with vaccination, along with excellent defense against serious symptoms leading to hospitalization and death, even if a breakthrough infection occurs.

Vaccine avoidance and emergence of new strains

However, at this time it seems clear that even after areas like South Asia and Africa (sources of the Delta and Omicron variants, respectively) have COVID‑19 vaccines available, there will be a significant portion of every nation/culture worldwide that will remain reluctant to receive a vaccination. The relatively low rates of hospitalization and death from COVID-19 (even in the unvaccinated) of those under age 50 or without serious comorbidity are such that most of these people do not know anyone personally who has gotten seriously ill with COVID-19. At even 15% of the world’s population, vaccine avoidance would provide over 1 billion humans in which the virus can mutate. Selectional pressure is strongest for increased viral transmissibility. Being able to evade vaccine protection would also be positively selected for. Increased lethality is a slight disadvantage for the virus but still could occur by chance in a highly transmissible variant.

The upshot of this convergence of issues is that SARS-CoV-2 is most likely here to stay for the foreseeable future, and humans will have to adapt to its presence in the biosphere, as we have already begun to do. Better vaccines and treatments will continue to be developed and drive down COVID-19-related death rates, while impacts on the global economy will gradually abate (but not disappear).

Never has the importance of biotechnology been more apparent than has been seen since the advent of the current pandemic. Some of the astounding changes brought on by the adaptation of this coronavirus to a human host have accelerated societal trends that were already in motion. Some business sectors have had their relevance and revenues drastically reduced. This is not the case for biotech. MarinBio stands ready to assist not only in pandemic-related projects but in all types of biopharma endeavors. The expertise of our scientific staff in flow cytometry, ELISAs, cell-based assays, and immunoassays spans decades. Contact MarinBio to consult with our scientists to see how we can be an effective and dependable partner.

Texas Biomedical Research Institute: https://www.txbiomed.org/news-press/news/dropping-antibodies-covid/

Journal reference: Salvagno GL, Henry B, Pighi L, De Nitto S, Lippi G. Total Anti-SARS-CoV-2 Antibodies Measured 6 Months After Pfizer-BioNTech COVID-19 Vaccination in Healthcare Workers. SSRN Electronic Journal, 2021; DOI: 10.2139/ssrn.3915349